Circuit breaker contact



April 1935- J. w. SEAMAN 2,037,544

CIRCUIT BREAKER CONTACT Filed Aug. 17, 1933 3/28 Irn/erflor' 61 Joseph WSeaman b H ATTorne Patented Apr. 14, 1936.

UNITED STATES 2,0375% CIRCUIT BREAKER con'rac'r' Joseph W. Seaman,Lansdowne, Pa, assignor to General Electric (Jompany, a corporation ofNew York Application August 17, 193?, Serial No. 685,572

8 Claims. (Cl. 200-46) My invention relates to circuit breakers of thetype arranged to be operated with a snap action between open and closedcircuit positions, and has for an object the provision of inexpensivecontacts having resilience in the contacts themselves for absorbing theblow incident to the engagement of the contacts in closing an electriccircuit.

While not limited thereto, my invention is particularly applicable tocircuit breakers wherein a movable contact is arranged for operationinto and out of abutting engagement with a stationary contact.Heretofore considerable difficulty has been experienced in the operationof a switch contact at high speed into engagement with its cooperatingcontact by reason of the fact that the movable contact upon striking itscooperating contact at a relatively high speed tends to rebound andoften does rebound sufficiently to draw an arc betweenthe contactswhereby they are welded together to such an extent that it is impossibleto separate the contacts in the normal manner.

In carrying out my invention in one form thereof, I provide one of thecontacts with a longitudinal slot or slots to thereby form resilientpor-' tions sothat when the other contact comes into engagement with itthe energy of the moving contact is largely dissipated by'the resilientportion of the slotted contact.

For a more complete understanding of my invention, reference should nowbe had to the drawing wherein I have shown in Fig. 1 my inventionapplied to a circuit breaker; Figs. 2 and 3 illustrate modifications ofthe construction of the contacts, while Fig. 4 shows an end view of thestationary contact shown in Fig. 1.

Referring now to the drawing, I have shown my invention in one form asapplied to a circuit breaker l0 consisting of an operating handle ll, anover-center spring I2 and alink l3. The operating handle II andthe link13 are mounted upon a stationary pivot pin I5." supported in'the frame(not shown). The over-center spring l2, forming a yieldable connectionbetween the handle II and the movable contact .I 6. serves to operatethe movable contact lfi'into and out of engagement with the stationarycontact. H with a snapaction. As shown, these contacts l6 and I1 areformed ofsolid cylindrical conductors. The overcenter (spring 12 biasesthe handle ll against the stationary stop 'l 9 securedto the frameandalso biases the link l3 against a sta-v is pivotally'gsecmed to themovable. contact 16..

vertical slot 222 formed in the movable contact It. If the operatinghandle It is rotated in a clockwise direction the over-center spring [2is moved past its dead center position and serves to operate the contactl6 into abutting engagement with the stationary contact I! with a snapaction. Rotation of the handle II in a clockwise direction is limited bythe stationary stop 24 and it will be seen that when the handle H engages the stop 24, the spring I2 biases the contact l6 into abuttingengagement with the contact II.

In order to absorb the blow delivered by the movable contact Hi, thestationary contact as shown is provided with two longitudinallyextending slots 28 and with a conical recess 29, the longitudinalslotsproviding four relatively stiff laterallyyieldable portions 28a. Themovable contact l6 has its end beveled somewhat to form a contactsurface 30 which can enter the recess 29. As shown in the drawing, thebeveled contact surface 30 and the contact surfaces formed by the wallsof the recess 29 are inclined at an angle of thirty degrees with respectto the center line C or the line of movement of the movable contact 5.Consequently, as the beveled contact surface 30 of the movable contactI6 is operated into the recess 29 a component of the force moving thecontact acts radially to spread the stationary contact sections 28aapart. As shown in the drawing, the abrupt beveled portion 36 insures anabutting engagement with the stationary contact I! so that there is nofrictional opposition to the operation of the movable contact from theclosed to the open circuit position. Since the stationary contact is ofresilient material, the resilient sections or portions 28a absorb theblow incident to the closing of the sectional area. As shown in Fig. 4,the portions 28a form sectors-ofthe cylindricalcontact l1. When thecontact lfi is snapped to the closed position the contact surface 30upon engaging the walls of the recess 29 causes the portions 28c toyield laterallya slight amount and thereby I absorbthe kinetic energyQfthe'm Vin'g parts'as workth e work required to move the portions 28a.Theangle between the contact surfaces I and the line of movement. ofthecontactl-fi while providing for lateral yieldingmovement of the prusin mr ric i lr ipp th m le portions28a. ,i s ;suiiicientlygreat, toprevent these contact surface 30. In other words the engagement of thecontacts is an abutting one, there being no frictional gripping actionbetween the engaging surfaces.

If the contact engaging surfaces were normal to the path of movement,the movable contact when operated at high speed into engagement with thestationary contact would tend to re bound sufficiently to cause an arcto form between the contacts. arcing at the contacts might cause thecontacts to weld together and prevent normal operation of the circuitbreaker. Furthermore, if the contacts were frictionally bound togetherthe proper snap action of the contacts could not be obtained.

Thus it will be observed that I have related or proportioned toeachother the strength of the overcenter spring i2 comprising the yieldableoperating means, the stiffness of the yieldable contact portions 28a andthe angle of the contact surfaces in such a manner that the contactportions 28a flex upon impact and thereby absorb the kinetic energystored in the movable contact after which the contact portions return totheir Consequently, an abutting relanormal shapes. tion is maintainedbetween the contacts.

As shown in Fig. 2, the movable contact 3| is provided withlongitudinally extending slots 32 and with a conical recess 33. In thismodification of my invention the stationary contact 34 has its end 35beveled. The resiliency of the portions 3|a of the movable contact 3iabsorbs the blow incident to the closing of theswitch and preventsarcing at the contacts during the closing operation.

In Fig. 3, I have shown a conical recess 38 in the slotted movablecontact 40 while the sta-' tionary contact 4| is provided withlongitudinal slots 42 and a beveled end 43. The operation is similar tothe arrangement described in connection with- Figs. 1 and 2, although inthe present modification the radial forces act on both contacts, theportions 4la of the stationary contact being bent laterally and inwardlyto absorb the kinetic energy of the movable contact whilst the portions4.5 of the movable contact are bent laterally and outwardly.

In each form of the invention shown the beveled portion of one contactslidably engages the conical recess of the other contact so that arelatively large contact area is obtained. However, one contact can bemade concave and the other convex to produce a substantial contact areaand to produce the radial component of force on .the resilient portionwhereby the tendency of the contacts to rebound is eliminated.Furthermore, in all forms of my invention it will be observed that theabutting engagement of the contacts insures a minimum frictionalresistance of the contacts when the circuit breaker is operated to theopen circuit position.

While I have shown a particular embodiment of my invention, it will beunderstood, of course, that I do not wish to be limited thereto sincemany modifications may be made, and I, therefore, contemplate by theappended claims to cover any such modifications as fall within the truespirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. A circuit breaker comprising cooperating Even a slight amount ofpredetermined amount of kinetic energy being stored in the movablecontact during its high speed movement, one of said abutting ends ofsaid contacts being provided with relatively stiff laterally yieldableportions, said contacts being formed with contact surfaces at asubstantial angle to the line of movement of said movable contactthereby to provide for fiexure of said relatively stiff portions toabsorb said kinetic energy to prevent separation of said contacts byrebound, the stiffness of said portions, the strength of said yieldableoperating means and said angle of said contact surfaces being related toeach other to provide for return of said portions to their normal shapesafter flexure to absorb said kinetic energy. v

2. A circuit breaker comprising cooperating movable and stationarycontacts, means mounting said movable contact for relative movement withrespect to said stationary contact, yieldable operating means for movingat high speed said movable contact into abutting engagement with saidstationary contact, a predetermined amount of kinetic energy beingstored in said movable contact and said yieldable means during its highspeed movement, one of said abutting ends of said contacts beingprovided with relatively stiff laterally yieldable portions, theabutting ends of said relatively stiff portions being formed to providecontact surfaces at a substantial angle to the line of movement of saidmovable contact, and the other of said abutting ends having a contactsurface substantially parallel to said first contact surfaces, saidangle of said contact surfaces having such a-value as to provide forflexure of said relatively stiff portions to absorb said kinetic energyto prevent separation of said contacts by rebound, the stifiness of saidportions, the strength of said yieldable operating means and said angleof said contact surfaces being related to each other to provide forreturn ofsaid portions to their normal shapes after flexure to absorbsaid kinetic energy.

3. A circuit breaker comprising a stationary stationary contact, apredetermined amount of kinetic energy being stored in said movablecontact and in said yieldable operating means during said high speedmovement of said movable contact, the abutting end of said stationarycontact being provided with relatively stiff laterally yieldableportions, said abutting ends of said portions being formed to providecontact surfaces at a substantial angle to the line of movement of saidmovable contact, and the abutting end of said movable contact having acontact surface substantially parallel to said contact surfaces, saidangle of said contact surfaces having such a value as to provide forilexure of said relatively stiff portions to absorb said kinetic energyto prevent separation of said contacts by rebound of said movablecontact, the stiffness of said portions, the strength of said yieldableoperating means and said angle of said contact surfaces being related toeach other to provide for return of said portions to their normal shapesafter fiexure to absorb said kinetic energy.

4. A circuit breaker comprising a movable contact and a stationarycontact, yieldable operating means for moving at high speed said movablecontact into abutting engagement with said stationary contact, apredetermined amount of kinetic energy being stored in said movableconangle of said contact surfaces having a value tact and in saidyieldable operating means during the high speed movement, the abuttingend of said movable contact being provided with relatively stifflaterally yieldable portions, and the abutting ends of said portionsbeing formed to provide contact surfaces at a substantial angle to theline of movement of said movable contact,

the abutting end of said stationary contact having a contact surfacesubstantially parallel to said contact surfaces, said angle of saidcontact surfaces having such a value as to provide for flexure of. saidrelatively stiff portions to absorb said kinetic energy to preventseparation of said contacts by rebound of said movable contact, thestiffness of said portions, the strength of said yieldable operatingmeans and said angle of said contact surfaces being related ,to eachother to provide for return of said portions totheir normal'shapes afterflexure to absorb said kinetic energy.

5. A circuit breaker comprising cooperating contacts, yieldableoperating means for relative- I ly moving at high speed one of saidcontacts into abutting engagement with'the other of said contacts, apredetermined amount of kinetic energy being stored in said movablecontact during the high speed movement, said contacts being providedwith relatively stiff laterally yieldable portions adjacent theirrespective abutting ends, the abutting end of one ofsaid contacts beingformed to provide a contact surface at a substantial angle to the lineof movement of said one contact and the other of said abutting endshaving a contact surface substantially parallel to said first contactsurface-said angle of said contact surfaces having such a value as toprovide for flexure of said relatively stiff portions to absorb saidkinetic energy to prevent separation of said contacts by rebound of.said onecontact, the stiffness of' said portions, the strength of saidyieldable operating, means and said angle of said contact surfaces beingrelated to each other. to provide for return of said portions to theirnormal shapes after flexure to absorb said kinetic energy.

6. A circuit @breaker comprising a stationary contact and amovablecontact, a link pivoted .at one end and connected at its otherend to said movable contact, an over-center spring connected to saidlink for operating said movable contact at high speed into abuttingengagement with said stationary contact,. a predetermined amount ofkinetic energy.being stored in said movable contact, said link and saidspring dur:

ing said high speed movement, one of said contacts being provided withrelatively stiff yieldable portions; said relatively stiff portionsbeing formed to provide abutting contact surfaces at a substantial angleto theline of movement of said movable contact, and the abutting end ofsaid other contact having a contact surface substantially paralleltosaidc'ontact surfaces, said turn of said portions to their normal shapesafter flexure to absorb said kinetic energy.

7. A circuit breaker comprising cooperating at high speed one of saidcontacts into abutting engagement with the other'of said contacts, apredetermined amount of kinetic energy being stored in said movablecontact during its high speed movement, one of said abutting ends ofsaid contacts being provided with relatively stiff yieldable portions,an abutting end of one of said contacts being formed to provide acontact surface at substantially an angle of thirty degrees to the lineof movement of said movable contact, and the other of said abutting endshaving a contact surface substantially parallel to said first contactsurface, said substantially thirty degree angle and said contactsurfaces providing for flexure of said relatively stiff portions toabsorb said kinetic energy to prevent separation of said contacts byrebound, the stiffness of said portions; the strength of said yieldableoperating means and said angle of said contact surfaces being related toeach other to provide for return of said portions to their normal shapesafter flexure to absorb said kinetic energy.

8. A circuit breaker comprising stationary and movable contacts, meansmounting said movable contact for relative movementwith respect providedwith a plurality of relatively stiff yieldable portions extending apredetermined distance from its abutting end, the free ends of saidpor-' tions being. formed to provide a plurality of concontacts,yieldable operating means for moving tact surfaces, each surface beinginclined at an angle of substantially thirty degrees to the line ofmovement of said movable contact, and the other of said abutting endshaving a contact surface substantially parallel to said plurality ofcontact surfaces, said angle of substantially thirty degrees providingfor flexure of said relatively stiff portions to absorb said kineticenergy to prevent separation of said contacts by rebound,

' the stiffness of said portions, the strength of said yieldableoperating means and said angle of said contact surfaces being related toeach other to provide for return of said portions to their normal shapesafter flexure to absorb said kinetic energy.

JOSEPH w., SEAMAN.

